i3 - September/October 2017 - 14

Tech

By Murray Slovick

A T EC H TO WATC H

 T 

he first thing you notice about electric car racing is
that it's relatively quiet. There is a high-pitched whining
sound but not nearly the eardrum shattering blasts you
get from NASCAR races at Talladega Superspeedway or the Indy
cars at the brickyard in Indianapolis. Formula E racing takes place
in the world's largest cities and not on race tracks, but in the
heart of the city; Hong Kong, Mexico City, Paris, Montreal,
Marrakech and New York were on the calendar this year and
Santiago, Rome and Sao Paolo are lining up for future races.
The FIA Formula E Qualcomm New
York City ePrix, held July 15-16, was
the first motor-racing event ever in the
metropolis. Formula E cars raced on
the streets of the Red Hook neighborhood in Brooklyn in two 43-lap events
on a 1.21 mile course.
The challenge of Formula E is to
find the most efficient way of using
the energy provided by the 164-cell,
28-kilowatt-hour lithium-ion battery
pack and applying it on the road. If you
own a Tesla, Chevy Bolt, Nissan Leaf
or any other electronic vehicle (EV)
you know what I am talking about.
Formula E, semiconductor company
Rohm is sponsoring and officially
partnering with the Venturi racing team.
Rohm developed new power device
technology using Silicon Carbide (SiC),
a compound of silicon and carbon produced using a crystal growth process
of sublimation and exposure to high
temperatures of about 2,000°C.
This material can withstand much
higher electric fields than conventional
silicon, and devices with SiC can work
with higher voltages and currents, which
increases power density and reduces
switching losses even under high
14

SEPTEMBER/OCTOBER 2017

Semiconductor
company Rohm
is sponsoring
and officially
partnering with
the Venturi
racing team.

Silicon Carbide has
been identified as
a material with the
potential to replace Si
devices in the near term because of its superior material advantages. This year Rohm
embedded SiC Schottky diodes, making the
unit 2 kilograms lighter than the inverter
for season two. Electric efficiency was
increased by 1.7 percent, while the volume
of heat extraction (read: cooling) components was reduced by 30 percent.

temperatures. The use of SiC allows
for an inverter (hang on, I'll describe
this momentarily) with reduced size
A Brief Explanation
and weight, which in turn allows for
A diode is a semiconductor device with
improved weight distribution in motor
two terminals, allowing the flow of current
sports and less power consumption.
in one direction only. A Schottky diode
In electric vehicles, power inverters and
(named after German physicist Walter H.
converters are used to "invert" battery pack Schottky), is a semiconductor diode formed
direct current (DC) to alternating current
by the junction of a semiconductor with
(AC) for motors that are used to propel the a metal. Incorporating SiC high-speed
vehicle down the road. They also convert
device construction into Schottky diodes
AC to DC to charge the battery pack. With
makes it possible to design parts that can
an electric drivetrain, the inverter controls Withstand higher voltages and contributes
the electric motor in a manner somewhat
to greater compactness of other circuit
equivalent to how the Engine Control Unit components due to increased power supply
(ECU) of a gas or diesel internal combusefficiency and higher frequency operation.
tion engine vehicle determines the vehicle's The substitution also allows for smaller
driving behavior. As a result,
heatsinks for cooling.
the range of the vehicle is
Now that you've mastered
directly related to the effidiodes, let me explain one
ciency of the main inverter.
other semiconductor compoThe range
There is a growing
of the vehicle nent that comes into play
demand for more efficient
here. MOSFETS are Metal
is directly
power converters with
Oxide Semiconductor Fieldrelated to the Effect Transistors and handle
higher power density and
efficiency
higher temp-erature operasignificant power levels.
of the main MOSFETs are useful for power
tion in Formula E racing.
Conventional silicon (Si)
amplifiers. They are also critiinverter.
power devices can no longer
cal components in high-voltage
meet the requirements.
switching in AC/DC and DC/
I T I S I N N O VAT I O N

Steven Tee/LAT/Formula E

Electric Car
Racing
is a Testbed
for New Tech
http://www.fiaformulae.com/en
i3 - September/October 2017

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